3rd millennium

In contemporary history, the third millennium is the current millennium in the Anno Domini or Common Era, under the Gregorian calendar. It began on 1 January 2001 (MMI) and will end on 31 December 3000 (MMM), spanning the 21st to 30th centuries.

Ongoing futures studies seek to understand what will likely continue and what could plausibly change in this period and beyond.

Predictions and forecasts not included on this timeline

 * Climate change
 * Extinction
 * List of dates predicted for apocalyptic events
 * List of future astronomical events
 * List of lunar eclipses in the 21st century
 * List of solar eclipses in the 21st century
 * List of time capsules
 * Near future centennial (bi, tri, ect..) events.
 * Near future in fiction
 * Predictions and claims for the Second Coming
 * Projections of population growth
 * Representative Concentration Pathway
 * Shared Socioeconomic Pathways
 * Works falling into the public domain in the United States

2000s

 * See: 2000
 * 2001
 * 2002
 * 2003
 * 2004
 * 2005
 * 2006
 * 2007
 * 2008
 * 2009

2010s

 * See: 2010
 * 2011
 * 2012
 * 2013
 * 2014
 * 2015
 * 2016
 * 2017
 * 2018
 * 2019

2020s

 * See: 2020
 * 2021
 * 2022
 * 2023
 * 2024
 * 2025
 * 2026
 * 2027
 * 2028
 * 2029

2040s

 * Rare alignment of the five naked-eye planets cluster within 7° of longitude, September 12, 2040.
 * 2040: End year of the Baku City Master Plan implementation.
 * 2041:
 * The Antarctic treaty is scheduled to come under review.
 * 2042:
 * 17 September: a common computing representation of date and time on IBM mainframe systems will overflow with potential results similar to the year 2000 problem.
 * 2047: On 1 July, the present "one country, two systems" arrangement in Hong Kong is scheduled to end, as it was guaranteed for 50 years starting from July 1, 1997, provided under the Hong Kong Basic Law. The agreement was raised by Deng Xiaoping to deal with Hong Kong's reunification with the People's Republic of China in 1997, and stipulated in the Sino-British Joint Declaration of 1984. What will be done is not stated in any document.
 * 2048: On 14 January, the Protocol on Environmental Protection to the Antarctic Treaty is scheduled to come up for review.
 * 2049: On 20 December, the present "one country, two systems" arrangement with Macau, guaranteed for 50 years starting from 20 December 1999, provided under the Basic Law and the Joint Declaration on the Question of Macau, will expire.

2050s

 * 2050:
 * The United Kingdom aims to reach net-zero carbon emissions in accordance with the Climate Change Act 2008.
 * Three-North Shelter Forest Program is expected to be completed.
 * The case files surrounding the 1943 death of the former lieutenant general of the Polish Army and first Prime Minister of the Polish government in exile, Władysław Sikorski, is expected to be declassified this year by the British government. Due to tensions between The United Kingdom, The Soviet Union, and Nazi Germany, the circumstances of his death has led to disputes over whether the crash was deliberate or not. The official conclusion by the British government is that the crash was accidental. However, the Polish government refused to endorse this report on the basis of a lack of conclusive findings and contradictions within the British evidence. In 2008 an investigation was opened by the Commission for the Prosecution of Crimes against the Polish Nation of the Institute of National Remembrance, and concluded in 2013 that there is not enough evidence to prove or disprove the sabotage theory.
 * 2051:
 * April: One of the METI messages Cosmic Call 1 sent from the 70-meter Eupatoria Planetary Radar in 1999 arrives at its destination, Gliese 777 star.
 * 2054:
 * Hawksbill Creek Agreement granting tax exemptions and special economic status for Freeport, Bahamas, is set to expire.

2060s

 * 2060:
 * The Chinese government aims for China to be carbon neutral.
 * Russia aims to be carbon neutral.
 * 2061:
 * 28 July: Halley's Comet will enter the inner solar system and is expected to be visible from Earth again after its last perihelion in 1986.
 * 31 December: Expiration of the Singapore-Malaysia Water Agreement.
 * All 6 reactors from the Fukushima Daiichi Nuclear Power Plant are planned to be decommissioned by this time. (30 to 40 years from 2021) However, according to a 2023 report by Voice of America, some experts have said "it would be impossible to remove all the melted fuel debris by 2051 and would take 50-100 years, if achieved at all."
 * 2065:
 * The process of cleanup and decommissioning the Chernobyl Nuclear Power Plant, following the 1986 Chernobyl disaster, is projected to be finished.

2070s

 * 2070: According to an announcement made by Indian prime minister Narendra Modi in 2021, India will be carbon neutral.
 * 2079: For computer software using unsigned 16-bit binary day counts and an epoch of 1 January 1900, the counts will overflow after 65,536 (216) days, which will occur on 6 June 2079.

2080s

 * 2084: The next transit of Earth from Mars will happen.
 * 2085: The "secret" letter of Queen Elizabeth II will be opened in Sydney, Australia.
 * 2088: The University of Bologna, the world's oldest university in continuous operation, will turn 1,000 years old.

2090s

 * 2090: The September 11th Victim Compensation Fund is set to expire.
 * 2092:
 * Work on cleaning up the site of the Oldbury Nuclear Power Station is scheduled to be complete in 2092 (early estimate).
 * 2094:
 * 7 April: Mercury transits Jupiter, this is the only known such event of the decade.
 * 2096:
 * Ash Wednesday will occur on February 29 (leap day) for the first time since the start of the Gregorian calendar in 1582.
 * 2099:
 * The 99-year lease for Kaufman Astoria Studios in Queens, New York City is set to expire.
 * Ontario regains control of the Ontario Highway 407 when its 99-year lease expires.
 * 2099 is the maximum year that can be set on computers with BIOS firmware, as well as Microsoft's Windows XP, Windows Vista, Windows 7, Windows 8, and Windows 8.1 operating systems, and Sony's PlayStation 2 and the Nintendo DS gaming platforms.

2100s

 * 2100:
 * Silverstein Properties' 99-year lease on the World Trade Center expires.

2100s

 * 2103: Per an agreement between the National Archives and Caroline Kennedy, the jacket Jackie Kennedy wore on the day John F. Kennedy was assassinated cannot be displayed in public until this year.
 * FAT file systems theoretically support dates up to 31 December 2107 (though officially only up to 31 December 2099).

2110s

 * The Chernobyl New Safe Confinement reaches end of designed lifetime in the 2110s.
 * 2111: The will of Prince Philip, Duke of Edinburgh is scheduled to become public knowledge.
 * 2112:
 * The will of Queen Elizabeth II is scheduled to become public knowledge.
 * 2115:
 * The first book from the Future Library project will be published, 100 years after being submitted by author Margaret Atwood.
 * The One Hundred Year Study on Artificial Intelligence (AI100) initiated by Stanford University will be concluded.
 * 100 Years, a film by Robert Rodriguez and John Malkovich, will be released 100 years after its development.
 * 2116: China Merchants Port's 99-year lease on Hambantota International Port in Sri Lanka is set to expire.
 * 2117: In relation to the 2115 release of the 100 Years short film, A song titled "100 Years", composed by Pharrell Williams, will be released to the public. The song was performed by Williams at a private party in Shanghai, China, in 2017. The song is said to have addressed global warming.

2140s

 * 2140: All of the roughly 21 million Bitcoins are expected to be mined.

2150s

 * 2155: The Year type in MySQL supports dates up to 31 December 2155.

2170s

 * 2178: On 23 March, Pluto will have completed its first full orbit since its discovery in 1930.

2180s

 * 2182: On 24 September, asteroid 101955 Bennu has a 1-in-2,700 chance of impacting Earth.

23rd century

 * 2206: For the first time since 1935, Earth will experience the maximum number of five solar eclipses in one year.
 * 2227–2247: Pluto will be closer to the Sun than Neptune for the first time since 1999.
 * 2240: On September 16, the Hebrew calendar will reach the year 6000, signaling the latest possible arrival of the Messiah.
 * 2265: Return of the Great Comet of 1861.
 * 2285: On March 22, Easter will occur on its earliest possible date for the first time since 1818.

24th century

 * 2333: It is projected that the Dounreay nuclear site will be safe to use for other purposes.
 * 2353: The date of Easter as conventionally calculated will be five weeks earlier than its hypothetical date according to astronomical principles, in a "negative equinoctial paradox". Along with 2372, this will be one of only two such occurrences between 2020 and 4000.
 * 2372: The date of Easter will see another "negative equinoctial paradox", this time four weeks earlier than its hypothetical date. This will be the last such occurrence before the year 4000.
 * 2386: If not repealed or otherwise voided, the Treaty of Windsor (1386) between England and Portugal, currently the oldest military alliance still in effect, will have stood for one thousand years.
 * 2391: Palm Sunday and Saint Patrick's Day will coincide for the first time since 1940; the "wearing of the shamrock and the palm together" was seen as presaging a great event in Ireland.
 * 2400: The first century leap year since 2000.

25th century

 * 2425: If not repealed or overridden, the annual funding increase of $325 per student to Wisconsin public schools, which began in 2023, will end.
 * 2439 (estimated): The "Across the Universe" message broadcast by NASA in 2008 will reach Polaris.

26th century

 * c. 2500: Climate projections predict a barren landscape for the Amazon rainforest amid low water levels due to vegetation decline.
 * 2531:
 * Professor Hiroshi Yoshida of Tohoku University conducted a study in 2024 which suggests every Japanese person will have the surname "Sato-san" unless a law regulating couples to a single surname isn't changed before this time.

27th century

 * 2640: On 5 September, the 639-year-long performance of John Cage's organ work As Slow as Possible (begun in 2001) is scheduled to finish at the St. Burchardi Church in Halberstadt, Germany.

28th century

 * Earth will experience 241 lunar eclipses.
 * 2800: The second century leap year in the 3rd millennium, in accordance with the Gregorian calendar. The Revised Julian Calendar, however, observes a leap year in 2900 instead; those Orthodox Churches (e.g. Greek) using the Revised Julian Calendar to calculate fixed-date feasts will, if no changes are made to the calendar before then, celebrate fixed-date feasts a day earlier than Catholic and Protestant churches from March 2800 until February 2900. For example, through this century, such Orthodox Churches will be celebrating Christmas Day while simultaneously Catholic and Protestant churches are marking Christmas Eve.

29th century

 * 2847: The St. Michael's Catholic Cemetery (Happy Valley) in Hong Kong lease on Wan Chai's Saint Fulan gentleman street will end after a 999-year lease, assuming no legal status changes before that date.
 * 2883: On 4 January, the CPR (Canadian Pacific Railway) lease on the O&Q (Ontario and Quebec) will end, after a 999-year lease.

30th century

 * 2999:
 * The Longplayer composition is set to finish on 31 December 2999, marking the end of the thousand-year piece of music, which began on 1 January 2000.